Hunting Geese - Using a Non-toxic Tungsten Shot

The deer season for 2012-13 is history, but that doesn’t mean that hunting season is over. Small game, like rabbits and squirrels, may still be hunted as well as grouse. But perhaps the most exciting hunting prospects are for geese.

Goose hunting can be fun and productive, and you do both the birds themselves and the landowners a favor by shooting a few. In recent years, the game officials have practically begged hunters to help keep the flocks under control with liberal limits and extended seasons. Yet, very few hunters take advantage.

One stumbling block is getting legal in the license department, which involves a trip to the long lines at the United States Postal Service to obtain a duck stamp. A hunter must also have a valid state hunting license and a Virginia Migratory Waterfowl Conservation Stamp. You also have to use a non-toxic shot such as steel, bismuth, tungsten or an approved allow – definitely not lead.

Make a note that your gun must be plugged to accept not more than three shells. In recent years, game laws allowed more than three shells for the deer season, and many shotguns used for deer are also used for geese.

 

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Addressing New Conflict Minerals Requirements

As companies spent the recent year-end holidays closing their fiscal books and creating program budgets for new products and services into 2013, a small and seemingly obscure clause in one of the widest reaching financial reform acts in modern history has added concern and challenge to product manufacturers across industry segments.

The Dodd-Frank Wall Street Reform and Consumer Protection Act of 2010 contains a small but very important section addressing so-called “conflict minerals” – referred to as 3TGs (tin, tantalum, tungsten, and gold) – harvested from the Democratic Republic of Congo and surrounding countries. The people in these areas are experiencing war atrocities, human slavery, and other human rights violations cited by the United Nations.

As such, Section 1502 of the Dodd-Frank Act suggested that this issue requires an aggressive supply chain reporting mandate. The U.S. Securities and Exchange Commission (SEC) made final rulings on this provision in late August 2012 ascribing any publicly traded company and their suppliers to “include a description of the measures it took to exercise due diligence on the conflict minerals’ source and chain of custody” and file a new SEC form SD beginning in 2014 for the 2013 calendar year. The initial reporting period for tracking compliance efforts begins in January, 2013.

Far-reaching Impacts

According to leading industry experts in the field, the effects of the conflict minerals provisions are extensive. “It’s not just whether you are a public company, in which case you for sure must report and show due diligence through your supply chain. Also, private companies and companies that are part of the US company’s supply chains will be affected, as the requirements are cascaded down the value chain. It has been suggested by the SEC that the number of companies that may contain trace elements of conflict minerals could be in excess of 280,000,” notes Thomas Bley, senior project manager for software maker iPoint-systems and participant in a number of industry work groups.

One of the challenges that make conflict mineral compliance to Dodd-Frank so encompassing is the level of trace elements of 3TGs found in most electronics components, used in everything from computers to automobiles to household appliances. It is difficult for one company on its own to trace the flow of materials in raw form back to the component suppliers, however Dodd-Frank requires even deeper due diligence to determine the actual location of the mineral smelter. Some organizations have stated publicly that obtaining declarations of conflict minerals to a level of only 40-60% is sufficient.

“That’s a risky proposition,” suggests Bley. “While there are no penalties for using conflict minerals in company products, the regulations require that a ‘reasonable country of origin inquiry’ is performed. Those companies that lag in this area risk ‘named and shamed’ by the consumer public and nongovernmental organizations (NGOs),” creating a possible impact on brand reputation and sales.

 

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the Uses of Tungsten Carbide Powder

Tungsten carbide is a tungsten-carbon compound that contains an equal number of carbon and tungsten atoms. It is a fine, gray-black powder that is pressed into various shapes for use in applications. According to "Handbook of Chemical Vapor Deposition," tungsten carbide is prepared by the reaction of carbon with tungsten metal at temperatures between 1,400 Celsius to 2000 Celsius. Tungsten carbide powder comes in many shapes, particle sizes, microstructures and chemical compositions, including fine tungsten monocarbide powder and macrocrystalline tungsten.

Hardfacing
Tungsten carbide powder is commonly used for hardfacing metals. Hardfacing is the process in which a tougher, harder material is applied to a softer base metal. Tungsten carbide improves the wear-resistant properties of a base metal. It is applied to mining equipment parts (shovel teeth, heel plates, bucket wheel excavator teeth, wear parts, crushing hammers, cutter drums and longwall miners), mineral processing equipment (hammers, chutes, pulverizing and grinding parts), earth-moving and construction equipment (grader blades, cutting edges, augers, trencher teeth, ground engaging tools and tunneling equipment), drilling tools, processing equipment and agriculture equipment (subsoilers, discs and injectors).

Diamond Tools
Tungsten carbide powder is used to manufacture tools used in the diamond industry, such as segments, grinding wheels and scape. According to the book "Exploring Advanced Manufacturing Technologies," tungsten carbide diamond cutting tools are made by sintering diamond powder to a tungsten carbide base and then cutting them into various shapes. These shapes are inserted or brazed in tool bodies and then ground to finished shape and sizes. Diamond tools are used to cut hard materials, such as stone, glass and porcelain.

Consumer Goods and Sports
Tungsten carbide is used in common consumer goods, including razor blades. Tungsten carbide powder is used in men's wedding bands to give them a dark hue and to improve their scratch-resistance. Tungsten carbide powder is used to make sporting equipment and devices, such as trekking poles, cross-country skis, bicycle studs and drive tracks for snowmobiles. Hikers and trekkers use tungsten carbide-tipped poles and walking sticks to reduce pressure on leg joints and for balance. They are effective in providing traction on rock surfaces.

 

 

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Use of Tungsten Welding Rods Containing Thorium

Tungsten inert gas (TIG) welding, also known as gas tungsten arc welding (GTAW), is an arc welding process that uses a tungsten electrode to transmit the electric arc to the work piece. Unlike other arc welding methods, the tungsten electrode does not provide material to the weld, so a separate filler rod is needed for that purpose. Some tungsten electrodes are made with a small amount of thorium, which is a radioactive material and improves the welding qualities of the electrode.

Welding With Tungsten
Tungsten has the highest melting point of all metals, so the electrode material does not melt when exposed to the high temperatures of the arc. Tungsten can be used to weld metals and specific alloys designed to have a high melting point. Even though the tungsten electrode doesn’t melt during the welding process, the electrode can wear or chip over time. The electrode can be reshaped to a conical or rounded shape using a grinder.

Electrodes That Contain Thorium
Thoriated tungsten electrodes are made from tungsten combined with 1 to 2 percent thorium in the form of thorium dioxide. Thoriated tungsten electrodes result in improved welding properties over pure tungsten electrodes. By using thoriated tungsten electrodes, welders find it easier to start the arc and maintain the arc, reduce weld contamination, carry a higher level of current, and achieve a longer electrode life through reduction in wear.

Concerns
Thorium is a radioactive element, so thoriated tungsten electrodes do emit some radioactivity, but the amount is relatively low. Thorium mainly emits alpha particles, which can’t pass through a sheet of paper, but could potentially damage skin tissue with prolonged exposure. Thoriated tungsten electrodes should be stored in a steel container marked with the radiation trefoil as an identifier.

The Natural Council on Radiation Protection and Measurements (NCRP) estimates that the average annual effective dose welders are exposed to when working with thoriated tungsten electrodes regularly, is a maximum of 16 millirem. The amount of background and medical doses incurred by members of the U.S. population each year is about 250 to 1,000+ millirem, so the exposure due to the thoriated tungsten electrodes is small. However, common sense safety precautions should be taken to avoid excessive exposure, including not carrying electrodes close to the body, and wearing standard welding equipment while performing TIG welding. Welders should wear a mask while grinding thoriated tungsten electrodes to avoid breathing in particulates from the grinding process.

 

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Tungsten Ceramic Rings

An incredibly strong and dense metal, tungsten can be combined with ceramic to make rings and other fine jewelry. Tungsten ceramic rings are becoming a popular choice for many wedding bands due to their durability and beauty.

Identification
Tungsten is a steel-gray metal. When paired with tungsten, ceramic is often polished black for greater contrast.

Strength
When processed with carbon at high temperatures, tungsten forms tungsten carbide, the hardest metallic substance in the world. Tungsten ceramic rings have unmatched strength.

Benefits
Tungsten ceramic polishes to a mirror-like finish. It's also highly resistant to abrasions and scratches. It would take deliberate scratching from diamonds or corundum to inflict any damage whatsoever.

Considerations
Tungsten ceramic rings, while nearly impervious to scratching, are not indestructible. Tungsten ceramic's hardness makes it slightly more brittle than traditional jewelry metals, meaning it can be crushed under severe stress.

Warning
Once manufactured, tungsten ceramic rings can not be resized due to tungsten's remarkable hardness.

 

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Tungsten in the Human Body

According to the Centers for Disease Control and Prevention (CDC), tungsten "is a naturally occurring steel-gray to tin-white metal or fine powder that comes from more than 20 different tungsten-bearing minerals." Its atomic number is 74, and its atomic symbol is W. Normally used to toughen steel, the increase of industrial activity in the United States has heightened the chances of people being exposed to tungsten.

Means of Exposure
People can be exposed to tungsten by drinking water, eating food or breathing air that has been contaminated by tungsten. Although tungsten is naturally present in the environment in small amounts as minerals, industrial plants that manufacture tungsten can release large quantities of tungsten into the air.

Entering and Leaving the Body
Tungsten enters the body through eating, drinking, touching or breathing. Scientists are unsure about the metabolism of tungsten in the body, but it does enter the bloodstream and is spread to all parts of the body. Most of the tungsten is quickly processed in the digestive system, leaving your body either through urine or feces.

Health Effects
When exposed to high levels of tungsten, the immediate effects on the body can be irritation of the skin, eyes, throat or nose. Long-term effects can involve a myriad of lung problems, most likely coughing, wheezing and shortness of breath. Many of the long-term effects have been attributed to the use of cobalt in the tungsten-refining and compounding processes. It is important to understand that these side effects are the result of long-term heavy exposure to tungsten, not the minimal exposure to tungsten that most people experience.

Inconclusive Research
Currently, there is not enough scientific research to determine whether tungsten exposure leads to leukemia or other forms of cancer. The general rule of thumb is the more a person is exposed to tungsten, the higher the likelihood of that person experiencing some health effects

 

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How Is Tungsten Obtained?

Finding Tungsten
Tungsten is often found in conjunction with other metals such as wolframite (the element in which tungsten was first discovered whose name means "devourer of tin") and scheelite. Around the world, China is the most common place that tungsten is found and mined, though other locales such as Austria, Bolivia and Portugal also have mines that produce respectable amounts of this metal for use in light bulbs, rockets, and in the case of some first world countries, spacecraft.

Refining the Tungsten
Once the ores containing tungsten have been mined from the earth, a process developed by those who discovered tungsten (the Elhuyar brothers Juan and Fausto who were chemists in the late 1700s) is used to purify the metal. The ore that contains the tungsten is crushed, cleaned and then treated with various alkalis so that tungsten trioxide is formed. The tungsten trioxide is then heated using either carbon or hydrogen gas, which then separates the tungsten metal from either the water vapor or the carbon dioxide that forms, depending on which gas was used in the heating and refining process.

The Final Step
Pure tungsten, which is often a whitish or a gray color once it's separated from the ore it was mined in, is in a state referred to as powered tungsten. If necessary, powered tungsten can be used right away without any further modifications. However, if there is no pressing need for the tungsten right then, it will be shaped into bars to be stored or transported. Given that tungsten is a relatively malleable and ductile metal, this process isn't a very difficult one.

 

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Tungsten Carbide Cutting Tools

The quality of a cutting tool can determine whether cuts will be smooth and clean or difficult and sloppy. A metal cutting tool's quality begins with the hardness and durability of its metal. According to the Society of Manufacturing Engineers, "carbide and carbide-coated tools cut about three to five times faster than high-speed steels" and "higher tungsten content increases wear resistance." There are tungsten carbide cutting tools for a wide variety of applications and, once you understand the breadth of their possible uses, you'll be able to choose one for professional, amateur or even industrial projects.

Circular Saw Blades
Circular blades surrounded by sharp, tungsten carbide-tipped teeth can be found in factories for manufacturing, carpenters' tool kits for milling---and in the home, because do-it-yourselfers can buy them at hardware stores. These circular saw blades are sized to fit not only in industrial machinery but also in standard table saws and hand-held circular saws. The most common tungsten carbide circular saw blades are not solid tungsten carbide; their body is typically tempered steel and only the cutting edges of the teeth are coated with tungsten carbide. A variation of the toothed saw blade is the grinding "wheel" or abrasive blade---still circular but without teeth. Their edge is coated with tungsten carbide and used to exert abrasive force as they grind through stone, ceramics and metal.

Reciprocating Saw Blades
Tungsten carbide coats the edges of blades for reciprocating saws, such as jigsaws and demolition reciprocal saws. The back-and-forth sawing motion of these types of saws is well-suited for abrasion, and their coating of tungsten carbide grit allows them to grind through metals, ceramics and masonry. Applications include removing cast iron pipes and metal fasteners during demolition or cutting access holes through stone and tile during remodeling.

Drill Bit Tools
Drill bits may be solid tungsten carbide or tipped with it to provide the speed, accuracy and wear resistance required by machine shops and high-precision manufacturing applications. Construction professionals and amateurs buy similar bits that attach to hand power drills, drill presses and hobbyist rotary tools. Precision drill bit and grinding tools with tungsten carbide tips might be used for milling or sculpting metal as well as decorative carving of stone and precious gemstones. As materials scientist Dale Wittmer stated in a Southern Illinois University publication, "Tungsten carbide tools have been the standard for over 50 years in the mining industry."

 

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Tungsten Applications - Lamps

Background

Osmium has the highest optical emission rate of all metals. Consequently, after Edison’s carbon filaments, it was used at the beginning of the lamp industry. Osmium’s big disadvantage is its high vapour pressure, resulting in a short lamp life. Tungsten withstands considerably higher temperatures than osmium and has a very low vapour pressure, resulting in more luminosity combined with a long lifetime.

Wire Properties

Tungsten wire possesses characteristics that have provided it with a unique place in the origin and growth of the lamp industry. The lamp industry represents the largest commercial application of tungsten wire. It is used in this application because it displays excellent creep resistance at elevated temperatures. Tungsten is an attractive lamp filament material because it has an extremely high melting temperature (~3680 K) and a low vapour pressure at high temperatures. Tungsten is also intrinsically brittle and, initially, this prevented the manufacture of tungsten wire. However, at the beginning of this century William Coolidge, working at the General Electric Company, pursued the idea of deforming tungsten at elevated temperatures in order to make small diameter tungsten wire. Two important findings of his work were, first, to develop a method to work a powder metallurgy ingot down to wire by using deformation at elevated temperatures; and, second, to produce a ductile material from this deformation. Today, the ability to handle tungsten wire and coil filaments without breakage is the backbone of the whole incandescent lamp industry.

Processing

The initial stages of thermomechanical processing of sintered tungsten ingot are usually performed by rolling and / or swaging. These operations allow large deformations at relatively high temperatures and during the initial stages of deformation the ingot reaches full density. By working the tungsten at elevated temperatures, the tungsten is maintained well above the ductile to brittle transition temperature but below the recrystallisation temperature. At various points during this deformation, anneals must be applied, or the tungsten will become overworked and begin to fracture. Finally, wire drawing is used to reduce the tungsten to its final desired diameter. At this point, the microstructure consists of fibres which have very high aspect ratios: they act like fibres in a rope and provide bend ductility.

It was not until the advent of transmission electron microscopy that potassium was located in small bubbles in the tungsten. It is these potassium bubbles which provide the wire with its unique high temperature creep resistance. Potassium is essentially insoluble in the tungsten. The bubbles are first formed from the doped powder in the ingot during sintering. During thermomechanical processing, these initial bubbles are drawn out into tubes. When the wire is annealed, these tubes break up to form the rows of bubbles.

Once wire drawing is complete, the tungsten can be coiled into a filament and recrystallised. When the wire is recrystallised, the grain boundaries interact with the potassium bubble rows as the boundaries migrate, giving rise to an interlocking grain structure.

‘Bamboo’ Structure

Recrystallized pure tungsten wire forms a bamboo structure: the grains occupy the entire wire diameter, and the boundaries are essentially perpendicular to the wire axis. At elevated temperatures, under the stress produced by gravity, these boundaries would slide past one another by diffusion and produce a rapid failure. However, when potassium is present in the wire, the interlocking grain structure reduces the rate of grain boundary sliding and extends the filament life. These bubbles continue to pin the grain boundaries at the temperatures of lamp operation, and thus maintain a stable microstructure during the life of the lamp.

Applications

Tungsten is used in many different types of incandescent lamps. The most common types are the general household lamps, automotive lamps, and reflector lamps for floodlight or projector applications. There are also many thousands of speciality lamps, which have a broad range of applications, such as audio-visual projectors, fibre-optical systems, video camera lights, airport runway markers, photocopiers, medical and scientific instruments, and stage or studio systems.

 

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Tungsten Applications - Electrical Applications

Properties

Tungsten is practically the only material used for electron emitters. Although other, more electropositive, metals would yield higher emission rates, the advantage of tungsten is its extremely low vapour pressure even at high temperatures.

This property is also important for electrical contact materials. While more conductive metals like copper or silver evaporate (erode) under the conditions of an electric arc, tungsten withstands these.


Applications

The following list illustrates some of the resulting tungsten applications:

•         Directly heated cathodes or heater coils for indirectly heated cathodes in cathode ray tubes for TV sets or computer displays, X-ray tubes, electron tubes, klystrons, magnetrons for microwave ovens;

•         Thoria or rare earth oxide alloyed rod electrodes for inert gas welding (TIG welding electrodes), as well as High Intensity Discharge (HID) lamps;

•         Tungsten disks for substrate of high power semiconductor rectifying devices;

•         Sintered pure tungsten electrical contacts

•         Sintered tungsten-copper or tungsten-silver electrical contacts for high-voltage breakers

•         Infiltrated tungsten-copper or tungsten-silver contacts, made from very coarse (50-150 µm) tungsten metal powder

•         High temperature furnace parts such as tungsten heating coils, reflectors and structural material

•         Tungsten / tungsten-rhenium thermocouples for measuring the temperature in such furnaces

•         X-ray tubes for medical use are not only equipped with a tungsten emitter coil, but also with a rotary (or static) anode made of tungsten or tungsten/ tungsten-rhenium. Important here are not only the low vapour pressure, but also tungsten’s good heat conductivity and the wavelength of the resulting X-rays

•         Calcium and/or magnesium tungstate is the phosphor in intensifying screens used with the X-ray photo films. These phosphors convert X-rays into visible (blue) light, resulting in a smaller X-ray charge for the patient

•         Modern business machines, such as photocopiers, facsimile machines, laser printers and air cleaners are equipped with tungsten charger wires. Not only drawn tungsten wire, but also electro-polished, gold-plated or platinum clad tungsten wires are used for this application

•         Ceramic circuit boards are printed by means of a metal paste. After printing, the metallic layer is sintered to form the conductor, and tungsten is a commonly used metal for this purpose

•         Modern computer processors like the 586 series and higher, generate a heat output per square centimetre similar to that of a household cooker surface. Tungsten-copper heat sinks and the processor fan remove the heat

In modern microelectronics, the advantages of tungsten are its good electrical and thermal conductivity, and its thermal expansion coefficient is almost the same as that of silicon. Tungsten plays an essential role, as the following examples show:

•         Ultra high purity tungsten, tungsten silicide and tungsten-titanium PVD sputtering targets are used in VLSI and ULSI DRAM chip technology. A W-Ti layer on a wafer acts as a diffusion barrier, while W and WSi layers function as electrical conductor materials.

•         In liquid crystal display (LCD) technology, ultra high purity molybdenum-tungsten alloy targets are now used instead of molybdenum-tantalum, resulting in improved definition of LCD panels.

 

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